Re: Generalised approach to storing address details
Date: 12 Dec 2006 08:32:53 -0800
Message-ID: <1165941173.791417.85590_at_16g2000cwy.googlegroups.com>
paul c a écrit :
> JOG wrote:
> >
> > On Dec 11, 11:19 pm, paul c <toledobythe..._at_oohay.ac> wrote:
> >
> >>Neo wrote:...
> >>
> >>
> >>>>You think that RM can't handle hierachies after I answered your demand on the *Brothers and Sisters* thread with a simple structure that perfectly met your criterias?
> >>
> >>>It is not that RM can't handle hierarchies, ...I would like to know how the RM handles hierarchies, without the aid of
> >>
> >>a builtin such as TTM's TCLOSE that is essentially outside the scope of
> >>the RM (eg., it seems to me that it does a transformation that can't be
> >>couched in fundamental RM terms.)
> >
> >
> > Hi Paul. Remember that hierarchies are just a subset of the big picture
> > given they are composed of binary relations. Given the RM is a
> > generalized model, handling n-ary relations, surely the question is
> > /why would it/ provide support for the special case of diadic
> > relationships? If RM natively supported transitive operation would it
> > still be an algebra? And if it did what would applying transitive
> > closure to a ternary relation mean exactly?
> > ...
>
> Thanks, those three questions are put better than mine and I especially
> like the last one. (I may have misunderstood the intent of Neo's
> statement, eg., "handle" can be taken in various ways, but it struck a
> nerve with me.)
> >> > handle the extra idiosyncracies and shortcuts of binary relations
> > When we draw a hierarchy on paper we are constructing a handy shortcut
> > (google hasse diagrams for their generalization), and if we enumerated
> > the underlying relation mathematically we would end up listing _all_ of
> > the ancestry ordered pairs, not just the local ones. So I reply mu and
> > unask your question. The RM can represent hierarchy more than happily,
> > but it is not imo the responsibility of a generalized data model to
> > specifically.
>
> Yes, can't argue with that and I would say that my understanding is that
> the RM can happily represent (by represent, I think I mean materialize
> pairs) one hierarchy at a time, ie., not two at a time, eg., parents and
> their children or ancestors and their descendents.
So? That's a design problem not and RM feasibility issue
Regards...
> p
Received on Tue Dec 12 2006 - 17:32:53 CET